WO2009108136A1

WO2009108136A1 - Substrate cavity semiconductor package

Info

Publication number: WO2009108136A1
Application number: PCT/SG2009/000076
Authority: WO
Inventors: Wei Fan; Chee Wai Albert Lu; Kai Meng Chua; Boon Keng Lok
Original assignee: Agency for Science Technology and Research Singapore
Current assignee: Agency for Science Technology and Research Singapore
Priority date: 2008-02-27
Filing date: 2009-02-27
Publication date: 2009-09-03
Anticipated expiration: 2010-08-27

Abstract

A semiconductor package (10), said package comprising: a substrate (12); a cavity (14) formed within the substrate; a semiconductor chip (16) situated in the cavity. The semiconductor chip comprises a plurality of circuit contacts (30) extending from the semiconductor chip, proximate a periphery of the cavity. Conductive traces (32) are formed on the top surface of the substrate, and electrical interconnections (34) bridge the circuit contacts of the semiconductor chip to the conductive traces of the substrate. Conveniently, the semiconductor chip may be flush with the top surface of the substrate. The circuit contacts may extend from the top surface of the semiconductor chip.

Description

SUBSTRATE CAVITY SEMICONDUCTOR PACKAGE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefits from U.S. Provisional Patent

Application No. 61/064,316 filed February 27, 2008, the contents of which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to semiconductor packages, and more particularly to a semiconductor package with a semiconductor chip mounted within a cavity of a substrate.

BACKGROUND OF THE INVENTION

[0003] Numerous semiconductor packages are known. Typical packages include a semiconductor chip - typically an integrated circuit - attached to a substrate.

[0004] Example attachment techniques include wire bonding the semiconductor chip to the substrate; flip-chip attachment of the semiconductor chip to the substrate; or a building up the substrate to the semiconductor chip.

[0005] Each of these attachment techniques is imperfect. For example, wire bonding requires relatively lengthy interconnects between the semiconductor chip and the substrate. These introduce parasitic inductance interfering with the signal path.

[0006] Similarly, flip-chip attachment introduces capacitive interconnection paths between the semiconductor chip and substrate.

[0007] Substrate build-up around the integrated circuit requires complex process steps and is not suitable for use with many types of integrative circuits such as sensors and organic electronic devices.

[0008] Accordingly, there is a need for a new semiconductor package.

SUMMARY OF THE INVENTION

[0009] In an exemplary embodiment of the present invention, a semiconductor package, includes a substrate; a cavity formed within the substrate; a semiconductor chip situated in the cavity; the semiconductor chip comprising a plurality of circuit contacts extending from the semiconductor chip, proximate a periphery of the cavity; a conductive layer formed on a top surface of the semiconductor chip; and electrical interconnections bridging the circuit interconnects to the conductive layer. Conveniently, the semiconductor chip may be flush with the top surface of the substrate. The circuit contacts may extend from the top surface of the semiconductor chip.

[0010] Other aspects and features of the present invention will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In the figures which illustrate by way of example only, embodiments of the present invention,

[0012] FIG. 1 is cross-sectional view of a semiconductor package, exemplary of an embodiment of the present invention;

[0013] FIG. 2 is top view of a semiconductor package, exemplary of an embodiment of the present invention;

[0014] FIG. 3 is cross-sectional view of another semiconductor package, exemplary of an embodiment of the present invention; and

[0015] FIG. 4 is cross-sectional view of another semiconductor package, exemplary of an embodiment of the present invention.

DETAILED DESCRIPTION

[0016] FIG.1 illustrates, in cross-section, a semiconductor package 10 exemplary of an embodiment of the present invention. Semiconductor package 10 includes a substrate 12 in which a cavity 14, extending from a top surface 26 is formed. An integrated circuit in the form of a semiconductor chip 16 is inserted into cavity 14. A thin adhesive layer 18 may be used to physically bond the integrated circuit 16 into cavity 14.

[0017] Filler 20, formed of the same or different material as adhesive layer 18 may fill any gap between the side walls of cavity 14 and semiconductor chip 16. Filler 20 may be formed of an epoxy.

[0018] A metal layer 24 including thermal vias 22 is formed at the bottom of cavity 14, and extends to an opposite outer surface 28 of package 10. Surface 28 may be covered with a metal layer.

[0019] Integrated circuit contacts 30, located at the periphery of semiconductor chip 16, proximate the interface between chip 16 and substrate 12, provide electrical connection to any circuit formed on semiconductor chip 16. The number of contacts 30 may depend on the nature of any circuit on chip 16, and may be limited by space available proximate the periphery of the top surface of chip 16. Circuit contacts 30 may be formed in number of ways. For example, they may be formed on the top surface of semiconductor chip 16, as conductive (e.g. metal) pads on semiconductor chip 16.

[0020] Conductive traces 32 may be printed on top surface 26 of substrate 12 to route electrical signals from and to semiconductor chip 16. Traces 32 on substrate 12 may interconnect a circuit on chip 16 to other circuits (also on semiconductor chips) provide input/outputs, electric power, or the like. Traces 32 may be formed of metal, such as silver, gold or the like. They may, for example, be ink, that is screen printed, deposited, or jet printed on surface 26.

[0021] An interconnecting material 34, such as silver may bridge the connection between contacts 30 on the top surface of integrated circuit chip 16 and traces 32 on top surface 26.

[0022] Optionally, an encapsulant (not shown) may be formed atop interconnecting material 34 to electrically insulate the interconnecting material, and optionally the entire top surface 26 (including conductive traces 32) of substrate 12. Alternatively, interconnecting material 34, and the remainder of top surface 26 may be separately coated. The encapsulant may be silicon, epoxy or another molding compound.

[0023] Substrate 12 may be formed as a low-temperature co-fired ceramic (LTCC) substrate. As will be appreciated, LTCC techniques allow multiple layers to be processed in parallel and aligned stack immediately prior to firing. Each layer may include conductive material arranged to interconnect chip 16 to an external circuit. Passive components, such as resistors and capacitors, may also be included in one or more of the layers. Conductive vias may interconnect multiple layers.

[0024] As will be appreciated, cavity 14 may be formed with a depth equal to the height (or thickness) of semiconductor chip 16, and a cross-sectional area equal to larger the size of chip 16. Cavity 14 may be formed by drilling, laser cutting or the like in one or more of the multiple layers used to form substrate 12. As such, chip 16 may in some embodiments be received to be substantially flush with the top surface 26 of substrate 12, and also generally flush with the interior wall(s) of cavity 14.

[0025] Conveniently, as the top surface of semiconductor chip 16 may be generally flush with the top surface 26 of substrate 12, the top surface of chip 16 may be exposed, allowing chip 16 to act as a light source (such as a light emitting diode, laser, or the like), a micro-electrical mechanical system (a MEMS device), a sensor or the like. Conveniently, heat generated by chip 16 may be dissipated through thermal vias 22, and metal layer 24 to surface 28.

[0026] As required, top surface 26 of substrate 12 may be encapsulated and thus hermetically sealed or waterproofed. Conveniently, inexpensive ink jetting/dispensing or screen printing may provide traces to interconnect the integrated circuit on the substrate.

[0027] As will be appreciated, substrate 12 may contain several integrated circuit chips, interconnected to each other by traces 32. To this end, FIG. 2 depicts a semiconductor package 110 (like package 10 - FIG. 1), exemplary of an embodiment of the present invention. Semiconductor package 110 includes a substrate 112 (like substrate 12), having a plurality of cavities 114. Each cavity 114 receives a semiconductor chip 116, and may be interconnected with the cavity 114 in the same way semiconductor chip 16 is interconnected with cavity 14 - FIG. 1. Each semiconductor chip 116 includes at least one contact point 130, bridged to traces 132 (like traces 32) formed atop the surface of substrate 112. The multiple semiconductor chips 116 are electrically interconnected by these traces 114. In the depicted embodiment, each semiconductor chip 116 contains one or more individual light emitting diodes (LED). In the depicted embodment, the multiple semiconductor chips 116 - and LEDs are interconnected in series, with the anode of one LED interconnected with the cathode of an adjacent LED. As will be readily appreciated, the nature or semi- conductor chips 116 and the number and types of interconnects may vary from application to application.

[0028] Conveniently, a metal layer and metal vias (like metal layer 24 and vias 22 - FIG. 1) may be formed beneath each cavity 114 to guide heat from semiconductor chips 116 to the bottom surface of substrate 112.

[0029] In yet another alternate embodiment, depicted in FIG. 3, a semiconductor package 210 includes a substrate 212 in which a cavity 214 is formed. Again, an integrated circuit in the form of a semiconductor chip 216 is inserted into cavity 214 and a thin adhesive layer 218 may be used to bond the semiconductor chip 216 into cavity 214. Again, filler 220 (like filler 20), formed of the same or different material as adhesive layer 218 may fill any gap between the side walls of cavity 214 and semiconductor chip 216. Filler 220 may be formed of an epoxy.

[0030] Integrated circuit contacts 230 located at the periphery of chip 216, proximate the interface between chip 216 and substrate 212 provide electrical connection to any circuit formed on chip 216.

[0031] Conductive traces 232 may be printed on the top surface of substrate 212 to route electrical signals from and to chip 216. Traces 232, however, lead to metal vias 242 extending into substrate 212. Formed within substrate 212 is an inner conductive layer 240 that may interconnect integrated chip 216 to other integrated circuits, provide input/outputs, electric power, or the like.

[0032] An interconnecting material 234, such as silver, gold or other suitable conductive material may bridge the connection between contacts 230 on the top surface of integrated circuit chip 216 and traces 232 on the top surface of substrate 212. An encapsulant 250 may be formed atop interconnecting material 234 to electrically insulate the interconnecting material 234.

[0033] Further metal vias 248 may extend from layer 240 to interconnection points on the top or bottom surface of substrate 212, at a location distant from chip 216. These may allow for interconnection of semiconductor package to an external circuit. In the depicted embodiment, vias 248 extend to connectors 252 proximate an edge of semiconductor package 210.

[0034] Substrate 212 may again be formed as an LTCC substrate. As will be appreciated, cavity 214 may again be formed with a size equal to chip 216 - and in particular having a depth equal to the height (or thickness) of chip 216. As such, chip 216 may be received to be flush with the top surface of substrate 212. In the depicted embodiment, semiconductor chip 216 may take the form of a sensor, having a sensing area exposed on the top surface of semiconductor package 200. The sensor may be an optical, chemical, or other sensor.

[0035] Again, semiconductor package 200 may be generally waterproof - heremetically sealed by encapsulant 250, while layer 240 is sealed by the remainder of substrate 212.

[0036] In yet a further embodiment depicted in FIG. 4, a semiconductor package 200' like semiconductor package 200 (FIG. 3) may include a semiconductor chip 216' in a cavity 214' retained by adhesive layer 218' and filler 220'. A conducting layer 240' (like conducting layer 240) is formed within substrate 212'. Vias 242' extend from the top surface 226' of substrate 210' to layer 240'. A further set of vias 260 extend from layer 240' to the opposite (bottom) surface 228' to a connector 262. Connector 262 may be a surface mount (SMT) connector.

[0037] Of course, the above described embodiments, are intended to be illustrative only and in no way limiting. The described embodiments of carrying out the invention, are susceptible to many modifications of form, arrangement of parts, details and order of operation. The invention, rather, is intended to encompass all such modification within its scope, as defined by the claims.

Claims

WHAT IS CLAIMED IS:

1. A semiconductor package, comprising:

a substrate;

a cavity formed within said substrate;

a semiconductor chip situated in said cavity; said semiconductor chip comprising a plurality of circuit contacts extending from said semiconductor chip, proximate a periphery of said cavity;

a conductive layer formed on a top surface of said semiconductor chip; and

electrical interconnections bridging said circuit interconnects to said conductive layer.

2. The semiconductor package of claim 1 , wherein said circuit contacts extend from a top surface of said semiconductor chip.

3. The semiconductor package of claim 1 or 2, wherein said cavity has a depth equal to the height of said semiconductor chip.

4. The semiconductor package of any one of claims 1 to 3, wherein said top surface of said semiconductor chip is generally flush with said top surface of said substrate.

5. The semiconductor package of any one of claims 1 to 4, wherein said circuit contacts are formed near a periphery of said semiconductor chip.

6. The semiconductor package of any one of claims 1 to 4, wherein said conductive layer is printed on said top surface of said substrate.

7. The semiconductor package of any one of claims 1 to 4, wherein said conductive layer is jet-printed on said top surface of said substrate.

8. The semiconductor package any one of claims 1 to 7, further comprising a metal layer extending from a bottom of said cavity to a bottom of said semiconductor package.

9. The semiconductor package of claim 8, wherein said bottom of said semiconductor package is covered with metal.

10. The semiconductor package of claim 8, wherein said metal layer comprises thermal vias.

11. The semiconductor package of any one of claims 1 to 10, comprising an encapsulant formed atop of said top surface of said substrate to insulate said electrical interconnections.

12. The semiconductor package of any one of claims 1 to 11 , wherein said semiconductor chip comprises an optical light source, a sensor, or a MEMs device.

13. The semiconductor package of any one of claims 1 to 12, wherein said substrate is formed as low temperature co-fired ceramic.

14. The semiconductor package of any one of claims 1 to 13, further comprising at least one additional cavity, and at least one additional semiconductor chip in said additional cavity, said additional semiconductor chip comprising a plurality of circuit interconnects extending from a top surface of said additional semiconductor chip, interconnected with said conductive layer.

15. The semiconductor package of claim 14, wherein said conductive layer electrically interconnects said semiconductor chip and said additional semiconductor chip.

16. The semiconductor package of any one of claims 1 to 15, further comprising a conductive layer formed within said substrate, and at least one conductive via extending from a said conductive layer formed on said top surface to said conductive layer formed within said substrate.

17. The semiconductor package of claim 16, further comprising at least one connector mounted on a top or bottom surface of said substrate, and interconnected with said conductive layer formed within said substrate.

18. The semiconductor package of any one of claims 1 to 17, further comprising an adhesive to glue said semiconductor chip to said substrate.

19. The semiconductor package of any one of claims 1 to 18, further comprising a filler to fill any volume between an outer wall of said cavity and said semiconductor chip.